Scheelite-type NaEr(MoO4)2
نویسندگان
چکیده
Explorations of the A(1+)-RE(3+)-Mo(6+)-O(2-) (A(1+) is an alkali metal cation, RE(3+) is a rare-earth metal cation) quaternary systems prepared by the high-temperature solution growth method led to the title structure, sodium erbium bis-(molyb-date), NaEr(MoO(4))(2). It is isostructural to the scheelite structure (CaWO(4)) and is composed of [MoO(4)](2-) tetra-hedra with symmetry and [(Na/Er)O(8)](14-) polyhedra. The [(Na/Er)O(8)](14-) polyhedron is a distorted tetra-gonal anti-prism, also with symmetry, with statistically mixed Na/Er atoms at its centre. There are two sets of Na/Er-O bond lengths [2.420 (4) and 2.435 (3) Å], but just one set of Mo-O bond lengths [1.774 (4) Å].
منابع مشابه
Defect Scheelite-Type Lanthanoid(III) Ortho-Oxomolybdates(VI) Ln0.667[MoO4] (Ln = Ce, Pr, Nd, and Sm) and Their Relationship to Zircon and the NaTl-Type Structure
The rare-earth metal(III) ortho-oxomolybdates with the formula Ln0.667[MoO4] (Ln = Ce, Pr, Nd, and Sm) and defect scheelite-type structure crystallize in the tetragonal space group I41/a (a = 533–525, c = 1183–1158 pm) with four formula units per unit cell. The Ln cations at Wyckoff position 4b exhibit a coordination sphere of eight oxygen atoms in the shape of a trigonal dodecahedron. The same...
متن کاملScheelite-type sodium neodymium(III) ortho-oxidomolybdate(VI), NaNd[MoO4]2
Scheelite-type NaNd[MoO(4)](2) contains one crystallographic position (site symmetry [Formula: see text]) for the large cations, which is mixed-occupied by Na(+) and Nd(3+) cations in a 1:1 molar ratio. Thus, both are surrounded by eight O atoms in the shape of a trigonal dodeca-hedron. Furthermore, the structure consists of crystallographically unique [MoO(4)](2-) units (site symmetry [Formula...
متن کاملThe defect scheelite-type lanthanum(III) ortho-oxidomolybdate(VI) La0.667[MoO4]
In scheelite-type La(0.667)[MoO(4)], one crystallographically unique position with site symmetry -4.. and an occupancy of 2/3 is found for the La(3+) cation. The cation is surrounded by eight O atoms in the shape of a trigonal dodeca-hedron. The structure also contains one [MoO(4)](2-) anion (site symmetry -4..), which is surrounded by eight vertex-attached La(3+) cations. The polyhedra around ...
متن کاملTriple molybdate scheelite-type upconversion phosphor NaCaLa(MoO4)3:Er3+/Yb3+: structural and spectroscopic properties.
Triple molybdate NaCaLa(1-x-y)(MoO4)3:xEr3+,yYb3+ (x = y = 0, x = 0.05 and y = 0.45, x = 0.1 and y = 0.2, x = 0.2 and y = 0) phosphors were successfully synthesized for the first time by the microwave sol-gel method. Well-crystallized particles formed after heat treatment at 900 °C for 16 h showed a fine and homogeneous morphology with particle sizes of 2-3 μm. The structures were refined by th...
متن کاملKEu(MoO4)2: Polymorphism, Structures, and Luminescent Properties
In this paper, with the example of two different polymorphs of KEu(MoO4)2, the influence of the ordering of the A-cations on the luminescent properties in scheelite related compounds (A′,A′′)n[(B′,B′′)O4]m is investigated. The polymorphs were synthesized using a solid state method. The study confirmed the existence of only two polymorphic forms at annealing temperature range 923−1203 K and ambi...
متن کامل